Tuner for cavity resonators



June 29,1948. y 'E ROSTAS, 2,444,066

TUNER FOR CAVITY RESONATORS Filed'uune s, 194:5

AGENT Patented June 29, 1948 TUNER FORv CAVITYRESONATORS Ernest Rostas,Lyon, France,` assigner to, International. Standardl ElectricCorporation, New

York, N. Y., a corporation, of Delaware Application June 3,' 1943;``Serial No; 489,474

e InA France May'll', 1940i section 1Pubiic. Law 69o, `August s, 194sPatent expires May1`1, 1960 6 Claims. (Cl. Z50-27.5)

Thenvention relates to systems for theadjustment ofresonant cavities.The resonance of. a :cavity intended to serve as an electric:4 resonatormay be adjusted by varying the volume .of this cavity either by meansof` a sliding piston, the surface-fof. whichiorms one Wall of thecavity,.or elsefloy` mechanically deforming one or more walls of`this.cavity elastically or permanently. 1Such methodsof, adjustmentbring about avariationlof they entire shape of.. thev cavity; this is,frequently troublesome andrequires-,devices (pistons, grippingorlocking,jaws-,.etc.)l whichtake up a relatively large amountof space insystems containingsuchcavities. .l e, e e l y e lOne object of vtheinvention istria-provision, for the adjustment of the electric resonanceof. a cav ity, of `means that necessitate no change of.` shape andApractically no change. of volume of sucha cavity. l l o `iiccording ytocertain of its characteristlcfeaf tures, the invention provides fortheadjustment. of a resonant cavity in whichv an electric `iield is set.up. andthe modification of thevconiguraton of,thiselectric eld or thedeformation Vof its lines of force, in part at least, in such a way asto` obtain. the desired.` resonance. H Y.

According lto one .featureor the` invention, such a deformation or.modilication of an electric eld within a resonant cavity is efected bythe'shiiting, of. ametallic or dielectricmember.withinthis cavity. e e eThe.invention` is explained in detail in thefiollowing description withreference to the appended drawingsin which: t y

Fig. lillustrates one example ofa resonant cav-- ity provid'edwith a`means. Iof adjustment according-to certain featuresof tl'ieinvention;` en Eigs. 2.and 3 illustrate twoexamplesofthe. application of e theadjustment means.- v ofl Fig. l. .to resonantcavities. L

. Fig, 4.-showsanother example of'an adjustment means, according tocertain featuresoiV the invention,` of the resonance; of a cavitysimilar to that of. Figs. 2 and. 3, and T e Fig', 5 illustrates `anassembly of tvvoL resonant. cavities Whoseadjustment is electedaccording. to features ofthe invention and which is part1cu1arlyintended to serve as an` oscillatory t cincuit in anA electrondischarge'device havingmodulation of VelOCitY r the electrons.`

Referring to Fig. 1, this shows a resonant cavity I delimited by a.dielectric discontinuity `2, for ex-` ample a conductvewall, with an`electric eldl within it. The distribution of this field is desig-` natedby lines of electric force 3the. variable spacing of which indicates thedensity of the :l'leldY in the. various. regions Vo1'.'cavity l.V Forexample.. Fig. 1 shows the eld'to be of great density around theraxis ofthe space withinthe limits 2; which, is assumed to be cylindrical,`and'this density di` min'ishes as Vthe Walls 2 are approached. Thiscavity has aninherent electric resonance which depends, as is known, onits physical dimensionsland onthe distribution of,V the electric iieldWithinA it..` Ithas hitherto been the regular practice to modify theelectric resonance sof a spaceof. this` kindby acting on its physicaldimensions., for example by using a piston as .one terminal Wallofcylinder 2', which results in modications ofV the electricaldistributionWithin it.

On. the. contrary and according to certain of its features, .the presentinvention pnovides.. means,` not vfor substantially modifying the shape.and the` mate-rial dimensionsof .the said space, but for actingdirectlyon. the `distribution of .the electric field Wlthinit. For example,asfshown in Fig. 1,.a conductiye Vorfdielectric elbow rod 4-5 (which mayalso be. an angle pla-te. or anelelment of dilerent asymmetrical shape)may be provided within .the

`cavity I, the. rod. 5V passing through the wallfin"` order to permit'control of the position ofthe `el' bow portion 4 within the cavity. The.presence of this rodl-E'will evidently modifythe; distributionoiitheelectric elda Within cavity l', but it is evident' that, whenthere is vrotation around-` rod' .i' as an a-xis, only 'theelbow'portion4' will then act to modify the distribution of the 'eld-and consequentlyto adjustzvolume l.V tothe desired.V electricxresonance. l

In a general way, the invention providesfwithln; resonant-spaces', theresonance: of Whichit. lsdesired .to be; able toadjust, an .element or.al member. of. such. shape that a movement.` of rotationv or translationimpartedto it brings it from one posi.-` tion where there isa certain.distribution of the lines of forceV of, theelectric eld to anotherposition Where this distribution was originally difierent,1"or examplefrom -the position indicated` atl' inlig. 1 by rotation to the positionindicated by the dotted lines at 4'.

According to the distribution of the electric 'field 3, it may bedesirable to push in or pull out portion 5 with or without rotating, theposition of portion I in order to bring the member li into a portion ofthe electric field of different intensity.

Figs. 2, 3 and 4 show some examples of the application of the inventionin the case of a special resonant space particularly intended to serveas a resonant cavity or rhumbatron in an electron` velocity modulationtube.v

In these drawings the resonant cavity is toroidal and is delimited by awall 6 that is reentrant at and 8 in such a way as to form twov faxialchannels. Openings which may be in the form of grids S and I areprovided at the ends facing these channels. In one of the plane faces of.the wall 6 there is provided a screw I I or other supporting Amemberwhich can be rotated and which carries within the toroidal space a bentmember or rod I2, for example of elbow shape like .l

a crank, the rotation of which in the electric field (not shown) set upwithin thecavity will per- Y 4 made adjustable, if desired, in the wayshown in Fig. 4.

Although the invention has been described for certain particularexamples, it is evident that it is by no means limited thereto, but mayon the contrary undergo numerous modifications and adaptations withoutdeparting from its scope. It consists essentially in adjusting theelectric resonance of a cavity by modification of the distribution ofthe electric field within it.

What is claimed is:

1. A cavity resonator having a restricted central portion constitutingpart of the electron path and an enlarged outer portion surrounding saidcentral portion, comprising means for adjusting the resonance of thecavity resonator which includes an electric field deforming memberasymmetrically located lin the outer part of the cavity mit adjustmentof the electric resonance of the cavity. -l K Instead of a bent rod ormember such as I2, it is evident .that the element for adjusting theelectric resonance may consist of a closed loop or of a conductive ordielectric plate rotated in the electric eld that exists within thecavity.` A loop of this kind is shown at I3 in Fig. 3.

` For adjusting theelectric resonance in a resonant space of this kind,it may suffice to simply modify the length by which a rod or plate ofconductivefor dielectric material penetrates in such a way as to modifythe electric eld in the vicinity of the central discontinuity 9-I0 ofythe space as slrown at I4 in Fig. 4.

Fig. 5 shows an example vof the application of a resonant adjustmentdevice that incorporates features of the invention to an oscillatorycircuit of a velocity modulated electr-on discharge system of the typecalled klystro/n.

` kIn this Fig. 5, the oscillatory circuit comprises an outer cylinderI5 in which three transverse walls I6, I1 and I8 are arranged inintimate electrical and mechanical contact therewith effected manysuitable manner. The end transverse walls I6 and I8 both have la tubularreentrant portion I9 and 20, and the mid-wall I1 comprises a tubularportion 2l that extends on each side ofthe wall in order to cooperatewith the tubu lar 'portions I9 or ZIJ and thus produce constrictions 22and 23 respectively in the spaces or cavities 24 and25that are thusdelimited. Furthermore, the mid-wall I1 has slots, such as those shownat 26, for the direct coupling of the two spaces 24 and 25.

The problem is to bring the two two spaces 24 and 25 to the sameelectric resonance. For this purpose, space '24, for examplais providedwith. a resonance adjustment means` according toyone variation of theinvention.l This means consists, for example, of an elbow rod 21 whichis carried by plug 28 and the position of which can beladjusted by thesame.

However, as the two spaces 24 and 25 are constructed in such a way as tobe as identical asv possible in order to permit such adjustment, it isnecessary to-likewise change the resonance of space by the same amountby which that of space 24 is changedas Va result of the presence of theelbowY rod 2l in its mid-position'. This is eiiectedfor example, bymeans of a rod like 29' as'shown in the drawing. This rodmay even beresonator andmovable therein for adjustment between positions ofdifferent electric field intensity, said electric eld deforming membercomprising va central rotatable axis member extend'- -ing from theinterior of the cavity resonator to the exterior thereof and an offsetportion extending radially from said axis member and lying within saidcavity resonator, whereby rotation of said axis member causes saidoffset portion to assume a series of positions asymmetrically related toone another and to the electric field within said cavity resonator.

2. A cavity resonator consisting of a rst and a second cavity resonatorelement through which elements an electron stream is to be passed insequence, comprising means for obtaining identical resonant frequenciesin the said cavity resonator elements, said means comprising an electriceld deforming member asymmetrically located with respect to the axis ofsaid field movably mounted in the lfirst cavity resonator forladjustment between positions of different electric ield intensity, saidelectric field deforming member comprising a central rotatable axismember extending from the 4interior of the first'cav-V ity resonatorelement to the exterior thereof and an offset portion extending radiallyfrom the said axis member and lying within said first cavity resonatorelement, whereby rotation of said axis member causes said offset portionto assume a series of positions asymmetrlcally related to one anotherand -to the electric field within said cav-` ity resonator.

3. A cavity resonator as set forth in claim l, including a second.discrete field deforming member mounted in ment.

4. A cavity resonator comprising means for ad-L justing the resonance ofthe cavity resonator including a member for deforming the electric eldin said cavity resonator, said member being asym-v metrically locatedwith respect to the axis of said' field and movable therein foradjusting between positions of different eld intensity, saidelectricfield deforming member comprising a central rotatable axismember extending from the interior of the cavity resonator to theexterior there-A of and an offset portion extending radially from saidaxis member `and lying within said cavity resonator, whereby rotation ofsaid axis member causes 'said' offset portion to assume a series ofpositions asymmetrically related to one another to the electric fieldwithin vsaid cavity resonator.

5.*A cavity resonator comprising means forr adjusting the `resonance ofthe `cavity resonator,

said means including a member for deforming:

nie electric nem in said ,cavity .fesmator Sam the second cavityresonator ele-j ing a first member extending radially from said 10 axismember and a second member extending at an angle from said first member.

6. A cavity resonator as set forth in claim 5, in which said secondmember has its axis parallel to the axis of said axis member. i

ERNEST ROSTAS.

6 REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,913,978 Ewen June 13, 19332,259,690 Hansen et al Oct. 21, 1941 2,280,824 Hansen et al Apr. 28,1942 2,281,717 Samuel May k5, 1942 2,306,282 Samuel Dec. 22, 19422,323,729 Ryan July 6, 1943 2,342,897 Goldstine Feb. 29, 1944 2,356,414Linder Aug. 22, 1944

